Hi Harry, I’m not sure if you heard of fitnessbuiler app, I use the fitness pro version where it allows me to do my clients measurements and track improvements, you can also create workouts specifically to your clients needs. I’ve been using it for about 2 yrs now. I hope this info can be of help to your question.
Wish you the best in your journey!!
Im not sure the type of training that you do but I deal mostly with folks trying to exercise to live pain-free, and everything is really centered around posture and movement qualify.
There two great apps if you do something similar.
The first is posture screen mobile. If it’s very cool because after you take pictures of your client it allows you to show exactly where deviations exist. The second app is from gray cook. He developed an app to use the functional movement screen and log your clients results.
Hope this helps,